Put the verbs in brackets in either the present perfect or the present perfect continuous:
1- Richard Branson, owner of Virgin Atlantic, (fly) balloons for many years. he still flies them today.
2-I know he ( make ) a transatlantic flight, but I´m not sure when
3- you ever (see) a hot-air balloon?
4-scientists (work) on a new plane but the work is not finished yet.
AJUTATI MA URGENT ....